High surface area ceramic materials, such as Mo2N and Mo2C, have been investigated for their useful material properties which include, but are not limited to: catalysts for methane reforming, ammonia synthesis, alcohol synthesis from syngas, hydrodesulfurization, and electrocatalysis for hydrogen evolution reaction [5-10]. Additionally, Mo2C and Mo2N are known to possess high electrical conductivity, which in combination with their notable material hardness provide the potential to function as corrosion-resistant supports for platinum in PEM fuel cells [3].
Synthesis methods of high surface area Mo2N and Mo2C have been reported using a variety of methods, which can be summarized by three main reaction categories: carbothermal reduction, carburization, and ammonolysis of MoO3 [11-17]. In all three cases the molybdenum precursors are typically MoO3, (NH4)6Mo7O24.4H2O (AHM), or (NH4)2MoO4 (AM), where molybdenum is initially hexavalent. During the reduction of the precursor, an intermediate tetravalent phase (MoO2) is formed which is the species directly converted to nitride or carbide. High rates of solid state diffusion of the intermediate oxide phase, along with slow reduction kinetics, often result in extensive grain growth and low surface area carbides and nitrides [18]. To avoid this, these methods routinely employ temperature programmed reduction reaction (TPR) as a means of minimizing grain growth and maximizing surface area. Although effective, TPR typically requires long synthesis times at elevated temperature due to the slow ramp rates involved in the TPR profile.
As a result, TPR may be cost prohibitive to the scaling of these methods. Accordingly, alternative reaction pathways which yield high surface area materials are desirable.